Although definitions may vary, recent executive summary of proceedings from a joint workshop defined periviable is the period occurring from 20 0/7 weeks to 25 6/7 weeks of gestation. Previable is used to describe the period before 20 weeks. “PROM” is prelabor rupture of membranes or rupture of membranes before the onset of labor. Prelabor rupture of membranes can also be referred to as premature rupture of membranes. From @mysmfm: Periviable PROM refers to instances of PROM occurring between 20